| Summary: | 碩士 === 國立交通大學 === 電子工程系 === 90 === In the era of deep submicron semiconductor fabrication, interconnect resistance-capacitance (RC) delay dominates the performance of whole integrated circuits (ICs). To mitigate the issue, two realistic methods are accepted popularly. The first method is to replace the aluminum wires with copper interconnects which offer lower resistivity. The second method is to use a lower dielectric constant material as the inter-metal dielectric (IMD). However, some difficulties come up in integrating low-k material with copper wires, including dielectric integrity and high diffusivity of copper ions. In order to prevent copper from penetrating into dielectric material under both high electric fields and operation temperature, barrier dielectric have been developed to enhance resistance to copper drift.
Silicon carbide (SixCy) with lower dielectric constant (k~4) is a promising barrier dielectric material to replace typically used silicon nitride (SixNy), (k~8). In this study, we will discuss the basic material properties of silicon carbide, such as FTIR, AES, SIMS and XPS analysis. It’s investigated that the properties of nitrogen-doped silicon carbide are much better than those of pure silicon carbide. Moreover, the electrical characteristics remain stable after O2-plasma ashing, thermal treatment and even BTS (bias-temperature-stress) in high electric field (up to 4MV/cm, 150oC, 1000 sec). These treatments are frequently implemented will be faced in the fabrication process. It’s also demonstrated clearly that the more nitrogen concentration of silicon carbide, the better barrier ability against copper diffusion. Finally, we find that the leakage behavior of silicon carbide is Poole-Frenkel transport which is similar to conventional amorphous silicon nitride film.
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